Monoidal categories with natural numbers object

The notion of a natural numbers object in a monoidal category is defined and it is shown that the theory of primitive recursive functions can be developed. This is done by considering the category of cocommutative comonoids which is cartesian, and where the theory of natural numbers objects is well developed. A number of examples illustrate the usefulness of the concept.This work was partially carried out while both authors were guests of McGill University and while the second author was a guest of Dalhousie University. Both authors acknowledge support from the Natural Sciences and Engineering Research Council of Canada and the Québec Department of Education.     

ETUDE COMPARATIVE DE L'IMAGE DE LA PSYCHOLOGIE CHEZ LES ETUDIANTS EN PSYCHOLOGIE,BELGES, ESPAGNOLS,FRANCAIS, MEXICAINS ET QUEBECOIS*

1373 psychology students from Barcelona (Spain), Liège (Belgium), Lille (France), Mexico city (Mexico) and Montréal (Canada) responded to a questionnaire dealing with their image of the discipline at various points in their university career. The students were asked to designate the authors they felt to be the most important as well as their preferences in regard to various areas and tendencies in psychology. The results show more agreement than could have been expected considering the cultural diversity and the great distance among the groups examined. Relevant differences from the other universities studied were found only with the Mexican students.     

Exteroceptive context in tasteaversion conditioning and extinction: odour, cage, and bottle stimuli

Five experiments investigated the extent to which the exteroceptive context, present on a saccharin aversion conditioning trial with rats, controlled the resulting aversion on one-bottle extinction tests and subsequent preference tests. The presence or absence of the specific odour which had been present on the conditioning trial was found not to influence saccharin intake on extinction tests, whereas the presence of the particular compartment in which, and the bottle from which, the saccharin had been consumed greatly suppressed saccharin intake as compared to the absence of these elements. Preference tests, performed in the respective conditioning contexts, showed extinction to be specific to the compartment + bottle context: groups that had extinguished their saccharin aversion in a context different from the conditioning context, retained their aversion in the conditioning context. No such specificity was found for the odour context. However, in the absence of the taste stimulus during the extinction phase, the odour that had been present on the conditioning trial did control the amount of water consumed, whereas the compartment+bottle context did not. Moreover, on preference tests, groups that had consumed water during extinction in the presence of the odour context, evidenced a lesser saccharin aversion than groups not exposed to the odour. The results are interpreted as demonstrating that rats learn about taste, odour, cage and bottle stimuli on a taste-aversion conditioning trial, and that taste and bottle stimuli seem to be the most salient.     

Catecholamine excretion in pleasant and unpleasant situations

Catecholamine excretion was studied in 36 students under four different conditions, which involved either playing a game of chance, performing psychological tests, watching surgical films or spending the session in inactivity. Adrenaline excretion was shown to be highest during the game session, which was described by the subjects in the most positive terms. It was concluded that a rise in behavioural arousal level is accompanied by increased adrenaline secretion, also when the arousal increase is induced by a situation regarded as pleasant.     

Size,convexity, and curvature magnitude estimations of curvilinear forms

Groups of Os made magnitude estimates of size, convexity, and curvature of patterns along a shape continuum. College Os repeated the procedure for a given physical measure in three successive sessions, but high school Os made only one set of estimates. The apparent size for the patterns was found to grow with an exponent between .700 and .755 for high school and college Os. The magnitude estimates for convexity and curvature were less reliable than the size estimates both between college and high school Os and within college Os over successive sessions. The magnitude estimates from the high school and college Os showed a faster apparent growth of curvature than of convexity.     

EFFECTS OF INTERSTIMULUS INTERVAL AND PREDICTABILITY OF EVENT STRUCTURE ON SERIAL REACTION TIME

A mean interstimulus interval (ISI) of 10 sec. resulted in significantly-shorter RTs to a single light stimulus than a 30 sec. average ISI. During a second workperiod the groups performing under each of the two ISI conditions were divided into four subgroups given 0, 25, 50 or 75% interspersion of an additional stimulus (sound). With short ISIs the condition of maximum predictability of event structure (light stimulus only) gave the shortest average RTs. With lessened predictability (increased proportion of the sound stimulus) there was a slight monotonous increase in RT. With long ISIs the same relationship was curvilinear, i.e. 25% interspersion of sound stimulus was most effective in preserving vigilance.     

ABILITIES OF TWINS

The investigation concerns two main problems: (1) the distribution of ability test scores among twins in comparison with single-borns; and (2) intra-pair similarity among the various twin categories. More than 1000 individual twins were compared with 2700 single-borns on 21 test variables covering Swedish, Mathematics and English. The twin group consistently showed a lower average than the single-borns due to a displacement of the test score distribution as a whole among twins. The intra-pair similarities, expressed as intra-class correlations, run between 0.85 and 0.90 for identical pairs, whereas like-sex fraternals showed coefficients about 0.60. The unlike-sex fraternals had coefficients ten to twenty hundredths lower than those of the like-sex pairs.